密度梯度离心结合贴壁法培养成年大鼠骨髓间充质干细胞的生物学特性

背景:研究骨髓间充质干细胞的培养方法,以获取大量高纯度的骨髓间充质干细胞,对应用组织工程技术重建眼部组织治疗眼部疾病具有重要意义。目的:应用密度梯度离心结合贴壁法进行成年大鼠骨髓间充质干细胞体外分离培养,观察其生长特性及大量繁殖的可能性。设计:完全随机分组设计/重复测量实验。单位:中山大学中山眼科中心病理科实验室。材料:选用6周龄SD大鼠4只,雌雄不限,清洁级2级,体质量约250g/只,由中山大学动物中心提供,许可证号码SCSK(粤2004/0011)。DMEM/F12培养基(美国GIBCo公司)、胎牛血清(杭州四季青生物工程公司)、胰蛋白酶、依地酸二钠、淋巴细胞分离液。纤维连接蛋白、CD44、CD34、CD31单克隆抗体,免疫组化二步法试剂盒(北京中杉生物技术公司)。方法:实验于2005-09/2006-01在中山大学中山眼科中心病理科实验室完成。①取SD大鼠,断颈处死后于750g/L酒精浸泡10min。无菌条件下,分离并暴露骨髓腔,用注射器吸入应用液直接插入股骨腔,用含肝素的培养液将骨髓腔里的细胞冲洗出来作为细胞混悬液,密度梯度离心结合贴壁培养法分离纯化大鼠骨髓间充质干细胞,观察活体细胞生长情况。②将第2代细胞接种于预置在培养板内的无菌盖玻片上,当细胞基本融合时,取出作原位甲醇固定10min,苏木精-伊红染色。原位丙酮固定10min,按二步法作免疫组织化学纤维连接蛋白、CD44、CD34、CD31反应,3,3’-二氨基联苯胺显色,最后将盖玻片反扣在载玻片上,封固、观察。③将细胞按4.25×107L-1的浓度接种于96孔板中,每孔200μL,置培养箱中,分别于接种后1,2,3,4,5,6d各于两排孔中加入20μL/孔四甲基偶氮唑盐,继续培养4h后吸去上清液,每孔加200μL二甲基亚砜,振荡5min后,于570nm波长测吸光度值,绘制细胞生长曲线。主要观察指标:①大鼠骨髓间充质干细胞活体培养观察结果。②2代细胞免疫组织化学染色观察结果。③接种后1,2,3,4,5,6d细胞生长曲线。结果:①刚接种入培养板的大鼠骨髓间充质干细胞于倒置显微镜下可见呈大小较一致的圆形,胞膜清晰,胞体透亮。第2天可见细胞已开始贴壁,3d后多数细胞伸出伪足,变成多角形、星形或不规则形。4d后细胞开始分裂繁殖,约12d细胞便基本单层融合,呈漩涡状排列。②对分离后所获得的细胞进行免疫组化染色,细胞CD44、纤维连接蛋白均阳性,CD34、CD31均阴性。③大鼠骨髓干细胞传代后第2天细胞数量就开始大量增加,至第5天数量达到顶点,细胞融合,生长达到平台期。结论:采用密度梯度离心结合贴壁培养法可获得较高纯度的骨髓间充质干细胞,是实用、便捷和可行的方法。并且在体外培养条件下能大量增殖,为应用组织工程技术治疗眼部疾病提供种子细胞。

Biological characteristics of bone marrow-derived mesenchymal stem cells cultured by density gradient centrifugation combined with adherence in adult rats

BACKGROUND: It is important to study the methods of culturing bone marrow-derived mesenchymal stem cells (MSCs) to obtain a great amount of high purity MSCs for applying ocular tissues constructed by tissue engineering technique to treat eye diseases.OBJECTTVE: To separate and culture in vitro MSCs from bone marrow of the adult rats by density gradient centrifugation combined with adherence culture, and observe the growing characteristics and the possibility of mass multiplication.DESIGN: A completely randomized grouping design/repetitive measuring experiment.SETTING: Pathological laboratory, Zhongshan Ophthalmic Center, Sun Yat-sen University.MATERIALS: Four six-week-old SD rats about 250 g, grade Ⅱ of cleaning, were provided by the Animal Center of Sun Yat-sen University [certificate number: SCSK(Yue)2004/0011], about 250 g each rat and there was no limit to the sex. The main reagents and instruments included low sugar Dulbecco modified Eagle culture medium (DMEM/F12, American Gibco Corporation), trypsin (fetal bovine serum (FBS, Hangzhou Sijiqing Bio-Engineering Material Research Institute), American Gibco Corporation), disodium edetate, lymphocyte separating medium, fibronectin, CD44, CD34, CD31 monoclonal antibodies, two-step-method kit for immunohistochemistry (Beijing Zhong shan Biotechnology Corporation).METHODS: This experiment was conducted at the Key laboratory of Ophthalmology (Sun Yat-sen University), Ministry of ethanol (750 g/L) for 10 minutes. Under aseptic condition, the medullaris cavitas was exposed, the syringe containing application m edium was directly punctured into the femoral cavity, the cells in the medullaris cavitas were washed out with the culture medium containing heparin and taken as the cell suspension. The bone marrow-derived MSCs were separated and purified by density gradient centrifugation combined with adherence culture, and the growing conditions of the wells. When the cells had generally connected with each other, they were fixed with methanol or dimethy ketone in situ for 10 minutes, and then hematoxylin eosin (HE) staining or immunohistochemical staining. Antibodies against fiinoculated to 96-well culture plate by a cell density of 4.25×107/L, with 200 μL every well; then put the culture plate into culture box. Then from the next day to the sixth day, 5 g/L MTT solution was added into two rows (20 μL every well) every day, continuously cultured for 4 hours, then the supernatant was removed, and 200 μL DMSO was added to each well, agitated for 5 minutes, then detected the absorbance (A) values at 570 nm wave length, and a growth curve was drawn.branes were clear and the cell bodies were lucent. Being cultured for 2 days, there appeared adherent cells. 3 days later,most of the adherent cells extended and appeared to be in polygon, star or long-shuttle shapes. 4 days later, the cells showed to be in division growth stage; and about 12 days later, the cell clones were connected to each other, appearing curve of subcultured MSCs was in S shape. Cells began growing fast on the 2nd day after being passaged, and they entered the growth period for 3-4 days followed by saturation period, and then cells stopped growing.CONCLUSION: It is a simple and practical method to separate MSCs from the bone marrow of adult rats by means of density gradient centrifugation and adherence. MSCs can greatly proliferate in vitro and offer seed cells for the application of tissue engineering technique to treat eye diseases.